1. Field of Invention
The present invention relates to technology for accessing a non-volatile memory. More particularly, the present invention relates to an accessing time adjustment for accessing a non-volatile memory.
2. Description of Related Art
Memory device in digital apparatus or digital is a necessary part. There are many kinds of non-volatile memory, such as NAND Type Flash devices, in the market for choice to the user. Taking the flash memory as the example, for different flash memory provider, the access time specification of the flash memory may be different. Even for the same Flash provider, although the Flash Access Time specification is the same, for the different Semiconductor Process, the “Real Acceptable Flash Access Time” has a lot of margin, compared to the timing rated in the specification. Even for the same Flash device, due to the operating voltage and thermal temperature variation, the Flash Access speed may be changed. In other words, for the mass production consideration with different process, voltage, temperature and some other factors, the Flash provider set the Flash Access Time specification in the lowest workable rate to guarantee some margins for these variations.
To speed up the Flash Access, performance is an important issue in many Flash Application such as DSC (Digital Still Camera), UFD (USB Flash Disk), Mobile Phone, et al. For many Flash Application fields, users always follow the Flash Specification to design their Flash interface circuit. Users try to speed up the Flash speed performance by using faster CPU or any other methodology. Although users do their best, there is a limitation in the Flash Access Timing Specification, on which users must follow to guarantee the Flash Data Access Correctness. However in real usage, there are a lot of margins in the access time. Like usual way in the Intel CPU case (386, 486, . . . ), the CPU operation Clock frequency have been rated in the Specification, but in the real usage, users can use faster Clock frequency (Over Specification) to get better CPU performance. However, the clock adjustment is done by hand, according to the user's specific experience.
A better solution to efficiently improve the performance is still in need under development.